Structure of [C₄mpyr][NTf₂] Room-Temperature Ionic Liquid at Charged Gold Interfaces

Abstract

The structure of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C(4)mpyr][NTf(2)]) room-temperature ionic liquid at an electrified gold interface was studied using neutron reflectometry, cyclic voltammetry, and differential capacitance measurements. Subtle differences were observed between the reflectivity data collected on a gold electrode at three different applied potentials. Detailed analysis of the fitted reflectivity data reveals an excess of [C(4)mpyr](+) at the interface, with the amount decreasing at increasingly positive potentials. A cation rich interface was found even at a positively charged electrode, which indicates a nonelectrostatic (specific) adsorption of [C(4)mpyr](+) onto the gold electrode.

Interfaces between Charged Surfaces and Ionic Liquids: Insights from Molecular Simulations

“…In previous studies, observations of similar structures were associated with the lattice saturation effect and the maximum of the differential capacitance curve (C diff vs. U). 30 However, Fig. 2 shows that within a distance of 1.7 nm from the electrode, there are also co-ions coordinated with several (2 to 4) counter- ions.…”

Local structures of ionic liquids in the presence of gold under high pressures

“…Some researchers have suggested the interplay between electrostatic interactions and steric hindrance at the interfaces. 15 Some studies also indicated that the abilities of a To whom correspondence should be addressed. E-mail: hcchang@mail.ndhu.edu.tw; Fax: +886-3-8633570; Phone: +886-3-8633585…”

“…21 The ordering of ionic liquids at solid surface is a subject of recent intense activities. [10][11][12][13][14][15] Based on these studies, solvation layers are found at the solid-ionic liquid interfaces for various ionic liquids. [10][11][12][13][14][15] As a matter of fact, ionic liquid may not be regarded as homogeneous solvent but must be considered as nano-structured with polar and nonpolar regions.…”

Neutron Reflectometry for Studying Corrosion and Corrosion Inhibition

“…There have been a number of related NR studies with in situ electrochemistry addressing an interesting range of challenges such as battery electrodes [107][108][109][110][111], solid electrolyte interface SEI formation [84], electroactive polymer films [112][113][114] and other double layer capacitance systems, such as ionic liquids at surfaces [56,115,116], as well as the formation and properties of passivating oxide layers [68,91,100].…”

“…Interestingly, they found there remained a cation surface excess even when the surface was positively charged, although at a lower concentration than when negatively charged. They ascribed this to the specific adsorption of the cation overcoming the electrostatic effects [115,116].…”